Precocious puberty (precociouspuberty) is defined as the appearance of secondary sexual characteristics in boys before the age of 9 years and in girls before the age of 8 years. According to the pathogenesis and clinical manifestations, it is divided into central (gonadotropin-releasing hormone-dependent) precocious puberty and peripheral (non-gonadotropin-releasing hormone-dependent) precocious puberty, which used to be called true precocious puberty and pseudococious puberty respectively. Central precociouspuberty (CPP) has a programmed process of hypothalamic-pituitary-gonadal axis (HPGA) initiation and maturation similar to normal pubertal development until the maturation of the reproductive system; that is, the hypothalamus secretes and releases gonadotropin-releasing hormone (GnRH) in advance, which activates the pituitary gland to secrete gonadotropin to develop the gonads and This leads to the development of internal and external genitalia and the appearance of secondary sexual characteristics. Peripheral precocious puberty is caused by the increase of sex steroid hormones in the body to the level of puberty due to various reasons, so only the early appearance of secondary sexual characteristics, but does not have a complete sexual development process. Central precocious puberty is caused by organic lesions of the central nervous system, such as hypothalamus, pituitary tumor or other central nervous system lesions. It is transformed from peripheral precocious puberty. If no organic pathology is found, it is called idiopathicCPP (ICPP). Incomplete central precocious puberty, a special type of CPP, refers to children with early appearance of secondary sexual characteristics, whose control mechanism also lies in the activation of the hypothalamic-pituitary-gonadal axis, but it is self-limiting in the development of sexual characteristics; the most common type is simple precocious breast development, which, if it occurs in girls within 2 years of age, may be due to the hypothalamic-gonadal axis being in a physiologically active state, also known as “micropuberty”. Girls have more ICPP, accounting for more than 80%-90% of CPP, while boys have the opposite, with more than 80% being organic. Peripheral precocious puberty Classification according to the characteristics of secondary sex characteristics: early appearance of secondary sex characteristics is called homosexual precocious puberty when it is the same as the original sex of the affected child, and heterosexual precocious puberty when it is opposite to the original sex. (1) Homosexual precocious puberty (secondary sex characteristics of girls): It is seen in genetic ovarian abnormalities such as McCune-Albright syndrome, benign ovarian occupational lesions such as autonomic ovarian cysts, estrogen-secreting adrenocortical tumors or ovarian tumors, ectopic human chorionic gonadotropin (HCG) secreting tumors, and exogenous estrogen intake. (2) Heterosexual precocious puberty (male secondary sexual characteristics): seen in congenital adrenocortical hyperplasia, androgen-secreting adrenocortical tumors or ovarian tumors, and exogenous androgen intake, etc. Boys (1) Homosexual precocious puberty (male secondary sexual characteristics): seen in congenital adrenocortical hyperplasia (more common), adrenocortical tumors or testicular mesenchymal cell tumors, ectopic HCG-secreting tumors, and exogenous androgen intake. (2) Heterosexual precocious puberty (female secondary sexual characteristics): seen in estrogen-producing adrenocortical tumors or testicular tumors, ectopic HCG-secreting tumors, and exogenous estrogen intake, etc.